Apparatus for speed governing



June 6, 1933. A. H. MEARS 1,912,353

APPARATUS FOR SPEED GOVERNING Filed June 30, 1951 2 Sheets-Sheet l June6, 1933. A. H. MEARS 1,912,853

APPARATUS FOR SPEED GOVERNING Filed June 30, 1951 2 Sheets-Sheet 2 l 63M O f l 94 a 80 85 at .m 79

6Z1 g 7 65 F .9 o 7 Patented June 6, 1933 UNITED STATES PATENT OFFICEATHERTON H. MEARS, OI PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO LEEDS &NORTHRUP COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA APPARATUS FOR SPEED GOVERNING Application filed June 30,

My invention relates to governor mechanism for maintaining constant thespeed of a motor used for timing purposes, or any purpose requiring highdegree of constancy.

In accordance with my invention, the effect of ambient temperature upona governor controlling the speed of a motor, is compensated by athermostatic element; more particularly a. bimetallic strip maintainsthe stiffness of the spring system of the governor constant irrespectiveof substantial variations in ambient temperature.

My invention further resides in the features of construction,combination and arrangement hereinafter described and claimed.

For an understanding of my invention and some of the various forms itmay take, reference is to be had to the accompanying drawings in which:

Fig. 1 is an elevational view of the rotatable governor structure, andFig. 1a is a modification thereof.

2 is an inverted plan view of stationary structure and elements movablysupported thereon.

Fig. 3 is an elevational view of the structure shown in Fig. 2.

Fig. 4 is a side elevational view showing in part the structure of Figs.1 and 2 in operative relation.

Fig. 5 is a view showing the relation between certain parts of thegoverning mechanism.

Fig. 6 is an elevational view, partly in section, illustrating anothertype of governor driven by and controlling the speed of a motor.

Fig. 7 is an elevational view on enlarged scale with parts in section ofthe governor shown in Fig. 6.

Fig. 8 is a top plan View of part of the stationary governor element.

Fig. 8a is a top plan view of part of the stationary element of anothermodification.

Fig. 9 is a bottom plan view of the rotatable governor element of Fig.7.

Fig. 10 is a detail view taken on line 1010, F ig. 7.

eferring to Figs. 1 to4 inclusive, frame 27 of the governor mechanism isattached to 1981. Serial No. 548,051.

the shaft 1 of a motor M whose speed is to be controlled, by a set screw10 or in any other desired manner. The centrifugal member or flyball 28which may be weighted in any well known manner, is attached to shaft 29through arm 28a rotatable in the upper end of bifurcated extension 30 offrame 27 and is freely movable between the head of the adjustable screw31, which passes freely through the weighted end thereof, and a stopframe 32 which threadedly receives the stop screw 31. Stop frame 32 issecured to frame 27 as by screw 13. A spring 33 passing through opening11 in hub portion 34 of the frame 27 and through the stop member 32engages at one end the movable centrifugal element 28, as by pin 12, andat its other end the pin 35 extending downwardly of frame 27.

A light frame work 36 movable with the flyball structure 28 passesfreely through a slot 14 in a hub portion 37 of frame 27. On the upperend of hub 37 is secured an eccentric cam 38. which operates in a mannerhereinafter described. Frame 36 terminates in a threaded rod portion 39extending substantially parallel to the axis of rotation of frame 27 andhas adjustably clamped thereto a disc 40 concentric with respect to theaxis of rotation of frame 27.

Referring more specifically to Figs. 2 and 3, a fixed supportingmember44 is adapted to be mounted independently of the motor M and itsrotating governor structure 27. Support 44 has pivotally mounted thereonat 43 a frame or switch-supporting member 42. As illustrated in Fig. 3member 42 is pivoted at one end, and at its other end has extending arms41, spaced as illustrated in Fig. 2, so as to engage the periphery ofcam 38 at diametrically opposite points. Member 42 has pivotally mountedthereon at 16 a switch member 47 which is bodily carried thereby. Itwill be apparent therefore that movement of the member 42 about itspivot 43 will also effect movement of switch member 47 in substantiallythe same manner. An insulating support 49, connected as by bolt 49a tothe fixed support 44, carries a fixed contact 48 which is adapted to beengaged by one end of switch member 47. Assuming that switch member -i-7is in engagement with contact a8 as indicated in Fig. 2, oscillation ofmember 42 about its pivot 43 will simply cause ro tation of switchmember d7 also about sub stantially the same point and switch member 47will remain in engagement with contact 48. In the same manner, switchmember 47, if out of engagement with contact l8, would remain in suchposition during oscillation of the switch-supporting member 42.

It now, however, the end of switch member on the other side of its pivot16 were to be kept from rotating with member d2, as by engagement withsome stationary member, it will be apparent that the contact engagingend of switch member 47 would oscillate through an are dependent on themovement of member 49, and would therefore intermittently engage contactas.

Referring to Fig. 4:, apparatus for oscillating member 42 isillustrated.

The periphery of the eccentric 38 is engaged by the lower edges of thedownwardly extending arms 41 of the frame or support 42 pivoted at 43.The fixed support let carries a cross arm d of suitable insulatingmaterial, the opposite ends of which are each provided with a bindingpost 46. Upon the frame 42, which adapted to be oscillated by cam 38during energization of motor M, the movable switch member 47, preferablya contact member, is suitably electrically connected to a terminal a6,as by conductor 15, and adapted to engage the contact e8 carried byblock 49. Contact i8 is electrically connected to a terminal 46 as by aconductor 17. Contact memher 1 7 is provided at its opposite end withtwo actuating arms 50 and 51 disposed in dii'i'erent planes, as shownmost clearly in Fig. 5, and adapted to alternately engage the disc 40during oscillation of frame 42 by cam when disc 40 is in predeterminedlimiting positions.

The reaction between the switch actuating arms and member 40 may be bestexplained by reference to Figs. 2, 8 and 5. Switch member 47 is cut awayas at 47a so that the members projecting above disc 40 may not interferewith movement of the disc with respect to the switch actuating arms 50and 51. Referring more particularly to Fig. 5, disc a0 is shown in itsneutral position and will not be engaged by either arm 50 or 51. In casedisc should take a lower posit-ion, due to increase in speed of motor M,it would be engaged by the laterally extending arm 51. In the samemanner, elevation of disc "1 0 womd put it in the path of arm 50 whichwould engage the disc, and thereupon actuate the switch member. Memberl7 is cut away as indicated in Fig. 3 so that disc will not engage anyportion of arm 51 until it has reached a predetermined low position.Stitch member &7 may comprise simply a metal stann ing having arms and51 bent at right angles thereto.

The governor thus far described is similar to that of my Patent1,797,510 granted March 24-, 1931 to which reference is here made formore detailed description of its operation.

It is characteristic of spring governors in general, that the speedwhich they maintain constant varies with changes in ambient temperature;i. e., the speed will be held constant at one value for a certaintemperature and at another value for a different ten'ipcrature. This isundesirable, particularly when the motor is utilized for timingpurposes, for example, for driving a recorder chart or sheet.

Upon decrease of ambient temperature, for example, the bracing action orforce exerted by the spring 33 tends to increase, as the length of thespring decreases, assuming that the material comprising it has apositive temperature coeflicient, and the elasticity of the springincreases. As a result, the governor holds the speed constant at ahigher value for the lower temperature. Conversely upon increase ofambient temperature, the governor holds the speed constant at a lowervalue. The integrated speed of the motor, or total number of revolutionsover a period of time therefore depends upon the ambient temperaturethough the motor speed is held constant for each temperature value.Changes in tcm perature may also affect the dimensions of other governorparts.

In accordance with my present in.ent-ion, the motor speed is madeindependent of ambient temperature or changes in ambient temperature, atleast throughout a substantial range of variation. In a governor of theconstruction described, the compensation is automatically appliedwhenever necessary and while the motor is running.

Referring to Fig. 1, the free end of an arm pivoted to a member 54extending below support -14, bears upon the top of the threadedextension 39 of the fly-ball frame 36. Between arm 58 and a thermostaticelement interposed an auxiliary spring 55 whose stiffness is less thanthat of the bimetallic strip 55. Assuming that spring 33 has a positivetemperature coetlicient, i. c. it lengthens with increase in temperatureand therefore becomes weaker 'ith higher temperatures, bimetallic stripis disposed with the metal havin the greater temperature coefiicient onthe under side so that strip as a whole curves downwardly upon. decreaseof temperature. The resulting increased compression of auxiliary spring56 compensates for the increased ision of spring 33 at the lowertemperature .naintaining constant the effective force restrainingmovement of the flyball by centrifugal action.

Conversely with in: e perature, the thermosm, a? relieves tocorresponding extent the compression of spring tee of ambient tcm- 56 sothat the differential of the forces exerted by spring 56 and 33 upon theflyball remains constant. Otherwise stated, thestifi ness of thegovernor spring system remains constant for changes in ambienttemperature so that the motor speed is independent of temperaturevariations. 3

More generally, the bimetallic stripmay compensate not only for theeffect of temperature upon the spring but upon other governor parts aswell or in other words for the net effect of temperature upon thegovernor.

The same result may be obtained with the construction shown in Fig. 1a.In this modification, the post of Fig. 1 for holding one end of governorspring 33 is replaced bythe bimetallic strip a Which bends upon changeof temperature to compensate for theeflt'ect of the temperature changeupon the governor. The arm 53, spring 56 and associated parts are ofcourse, omitted. The remainder of the governor construction is the sameas that of Figs. 1 to 5.

My invention is not limited for use with my harmonic governor but isapplicable to any governor whosespring tension may be varied while themotor is running. In Figs. 6 to 10, there is illustrated a governorsimilar to that disclosed and claimed in copending Wunsch applicationSerial No. 158,372, filed December 31, 1926, suitably modified toinclude the feature of compensating for the effect of temperature.

Referring to Fig. 6, M is a motor having a rotatable armature fastenedona shaft 61 mounted in bearings in the usual manner. A worm gear 62fastened to the shaft 61 is in engagement with a worm wheel 63 to drivea shaft 64 connected by means of the gear 65' to any suitable device ormechanism whose speed is to be controlled with great precision. It is tobe understood, however, that such mechanism may be directly driven fromthe shaft 61. The rotatable element 66 of the governor is held in anysuitable manner, such as by a set screw, to an end of the shaft 61 androtates therewith. The stationary or contact-carrying member of thegovernor 67. is rigidly clamped to the housing 68 which may also serveas a mounting for the motor M, as shown.

The hub portion of the rotating or centrifugal element 66 is providedwith a bore 69 to receive an extensionv of the shaft 61,

which is locked in position by means of a into the yoke member, isutilized as an adjustable stop for moving the slotted member 72 toobtain a desired tension of the spring 73.

The head of the screw 72a, extends through.

the slot in member 72 to facilitate anadjustment of t-he'screw by meansof a screw-driver, or other suitable tool. I When the desired adjustmenthas been made, the screw may be locked in position by the clamping screw7 26, or in any other suitable manner. The spring 73, passes through ahole in the hub portion of the movable member 66, and is fastened at itsother end to the threaded extension of a flyball 74, secured to oneextremity of a pivotal member 75. The other extremity of the member 75,which is pivoted on pin 76, is provided with downwardly extending lugs75a, having each a hooked portion for a purpose hereinafter described.Passing through the same end of this member and held fast thereto bymeans of the clamping nuts .78,is a bearing member 77, preferably offibre, which cooperates with a part of the stationary orcontact-carrying structure in the axis of rotation of the rotatingelement. When the speed of the motor is below the desired or criticalspeed, the member 75 is biased by means of the spring 73 to the positionshown in Fig. 7. The strength of the spring bias, as previouslydescribed, is adjustable by means of the screw 72a and the lever 72.When the motor speed is higher than the desired speed, the centrifugalforce acting on the flyball 7 4 overcomes the tension of the spring 73,modified as hereinafter described, and causes member 7 5 to rotate aboutpin 76 in a clockwise direction.

The stationary or contact-carrying member of the governor consists of aplate 79, having a pair of upturned lugs 80, through which extends thepivot pin 81. A movable member 82, is provided with bearings in a pairof projecting ears, which cooperate with the pin 81. On one side of thepivot, the member 82 has a slot 83, to provide a ready means foradjustably positioning a movable contact member-84, which is held in thedesired position by a nut or other suitable means. On the'other side ofthe pivot point, the member 82 has an extension 85 bent at an anglethereto, which receives an end of a relatively-fine, tension spring 86.The plate 79 is formed with an upwardly extending portion 103, whichlocates the pin 88a, on which is pivoted the bifurcated L-shaped member88, to which is attached the bimetallic strip 55' engaging the other endof the spring 86. [A screw 88b is threaded into a tapped hole in theupstanding portion 103 and has a shoulder portion which serves as anadjustable limiting-stop for the member 88. An extension of this screwpasses through a slot in the member 88, to'provide a ready means foradjusting the tension of the spring 86. The'bimetallic strip 55 ismaterially stiffer than spring 86.

The movable member 2 is provided with a button 87, preferably made ofsome wear-resisting material or hardened to prevent wear, which isintended to be in contact with the fiber bearing member 77 of therotating element, during normal operation of the governor. This member,which is fastened in any suitable manner to the member 82, such as byriveting, is so shaped that the hooked portions of the downwardlyextending ears 75a of the member 75 may, under circumstances to be laterdescribed, cause the rotation of the movable member 82 about its axis81.

It should be noted at this point that the spring 86 tends to cause therotation of the movable member 82 in a clockwise direction, and, sincethis member is, by means of the button 87, in engagement with the member75, it also tends to cause the clockwise rotation of the latter aboutits axis 76, which tendency is contrary to that due to spring 73. lVhenthe device is at rest, the screw 72a may be adjusted to regulate thetension of spring 73 through a considerable range, which serves as arough adjustment for approximating a desired speed or angular velocity.Since the spring 86 is opposite in effect on the member 75 to that ofspring 73 and the adjusting means therefor is on the stationary plate79, it is apparent that a desired operatin velocity of the governor canbe precisely efiected by this latter adjustment, even while the motor isrunning.

The relative positions of the movable and stationary members of thegovernor are such that when the motor is running below the criticalspeed, the bearing members 77 and S? are just touching in line with theaxis of rotation of the centrifugal member, and the contacts are closed."When the speed of the motor rises above that point, the member 75rotates in a clockwise direction about its axis 76 as described and thecontact member 82 follows it under the influence of spring 86. If,however, the contacts tend to stick or weld, the hooked portions 75a, ofthe member 75, after a slight movement, engage the under side of thebutton 87 and cause positive movement of member to separate them.

A threaded member 89 is riveted or otherwise fastened to the plate 79and serves both as a means for conducting the current to the movablecontact and for holding the plate in a. fixed position. The contact 91is carried by a slotted bracket extending from a ring 92, which is incontact with a threaded sleeve 93, surrounding the extension 89, butinsu la rd therefrom by the sleeve of insulation 99 and separated fromthe plate 79 by an inul iting washer 95. An insulating collar 100prevents the sleeve from making contact with the housing 68. A log 94,in contact with the sleeve 93, provides a means for conducting currentto the stationary contact 91.

The nut 98, threaded on the flanged sleeve 93, clamps ring 92, lug 9iand insulating washers 96 and 97 to the housing, as shown in Fig. 7. Theplate 79 is held rigid with this assembly by means of the clamping nut101 and the insulating washer 102.

The effect of ambient temperature upon the spring system-er the governoris compensated by the bimetallic element 55 substantially in the mannerpreviously described in connection with the preceding modification. Thebimetallic element 55 bends to the left as viewed in Fig. 8 upondecrease of ambient temperature increasing the tension of spring 86 tocounteract the increased tension of spring 73 and conversely uponincrease of temperature the tension of spring 86 relieved by bending ofthe bimetallic element to the right. In some cases, if the effect oftemperature upon spring 86 is greater than its effect upon spring 73, itmay be necessary to reverse the bimetallic strip to obtain thecompensating action.

A further modification of my compensating system is shown in Fig. 8a,which in some respects is more similar to Fig. 1 than Fig. 8 in that thebimetallic element 55 aries the compression of a spring 56 with changeof temperature. Ordinarily the bin'ietallic ele ment is so disposed thatupon decrease in ambient temperature, the compression of spring 56 isincreased which increases the tension of spring 86 to otlset theincreased tension of spring 73 and vice versa. In this arrangement thebimetallic element should be stiffer than spring 56' which in turn isstiffer than spring 86.

From the examples given, the manner in. which temperature compensationmay be applied to other types of spring governors readily understood andin its broader aspects my invention is not limited to the mechanismsspecifically illustrated and described.-

hat I claim is:

1. A governor system for a motor compris ing rotatable structure, acentrifugal member carried thereby, a spring opposing movement of saidmember by centrifugal force and rotatable with said structure, astationary support, a member pivoted thereon and engaging saidcentrifugal member in the axis of rotation of said structure, a springexerting a force on said pivoted membe the re sultant of the forcesexerted by said springs determining the speed of said motor, and athermostatic element controlling the force exerted by said secondspring.

2. A governor system for a motor comprising rotatable structure, aeentri'l'u'ml mcmher carried thereby, a spring oppo g move ment of saidmember centrifugal force and rotatable with said structure, a stationarysupport, a member pivoted thereon and en gaging said member in the axisof rotation of said structure, a spring exerting a force on said member,and a bimetallic strip Whose stiffness is greater than the stiffness ofsaid second spring Varying the force exerted thereby With changes oftemperature to compensate for the effect of the temperature changes uponsaid first spring.

3. A governor system for a motor comprising rotatable structure, acentrifugal member carried thereby, a spring system opposing movement ofsaid member by centrifugal force comprising a spring rotatable with saidstructure, and a second spring, a stationary support, a member pivotedthereon and biased by said second spring into engagement with saidmember in the axis of rotation of said structure, and a bimetallic stripfor varying the force exerted by said second spring with changes oftemperature to maintain the stiffness of the governor spring systemsubstantially constant throughout a range of temperatures.

4. A governor system for a motor comprising a centrifugal member,springs for producing forces Whose resultant opposes movement of saidmember by centrifugal force, means for adjusting at least one of saidsprings to obtain a desired value of said resultant force, and athermostatic element for varying the force exerted by at least one ofsaid springs to maintain said resultant constant at the adjusted valueirrespective of ambient temperature.

5. A governor system for a motor comprising rotatable structure, acentrifugal member carried thereby, a spring opposing movement of saidmember by centrifugal force and rotatable With said structure, means foradjusting said spring While said structure is stationary approximatelyto predetermine the speed of said motor, a stationary support, a memberpivoted thereon and engaging said centrifugal member in the axis ofrotation of said structure, a spring exerting a force on said pivotedmember, means for adjusting said second spring precisely to determinethe speed of said motor While running, and a thermostatic elementcontrolling said second spring to maintain the motor speed constant at afixed magnitude throughout a range of temperature.

ATHERTON H. MEARS.

